# Import necessary libraries
import numpy as np
import joblib  # For loading the serialized model
import pandas as pd  # For data manipulation
import logging # Added to generate logs for debugging purpose
from flask import Flask, request, jsonify  # For creating the Flask API


# Initialize the Flask application
product_sales_predictor_api = Flask("SuperKart Product Sales Predictor")

# Load the trained machine learning model
model = joblib.load("SuperKart_Sales_prediction_model_v1_0.joblib")

# Define a route for the home page (GET request)
@product_sales_predictor_api.get('/')
def home():
    """
    This function handles GET requests to the root URL ('/') of the API.
    The function displays simple welcome message.
    """

    # message added  as part of debugging process to check the function was getting invoked
    # code retained as it is after debugging
    handler = logging.FileHandler('app.log')
    product_sales_predictor_api.logger.addHandler(handler)
    product_sales_predictor_api.logger.setLevel(logging.INFO)
    product_sales_predictor_api.logger.info('GET INVOKED')

    return "Welcome to the SuperKart Product Sales Prediction API!"


# Define an endpoint for single Product Sales prediction (POST request)
@product_sales_predictor_api.post('/v1/ProductSale')
def predict_Product_Sales():
    """
    This function handles POST requests to the '/v1/ProductSale' endpoint.
    It expects a JSON payload containing Proeduct details and returns
    the predicted sales price as a JSON response.
    """

    #All types of logging enabled when issue was faced in endpoint access.
    #code retained as it is after debugging
    product_sales_predictor_api.logger.info('single prediction entered')
    
    print(">>> product endpoint invoked!", flush=True)
    # Get the JSON data from the request body
    product_data = request.get_json()

    # Extract relevant features from the JSON data
    sample = {
        'Product_Type': product_data['Product_Type'],
        'Product_MRP': product_data['Product_MRP'],
        'Product_Weight': product_data['Product_Weight'],
        'Product_Sugar_Content': product_data['Product_Sugar_Content'],
        'Product_Allocated_Area': product_data['Product_Allocated_Area'],
        'Store_Size': product_data['Store_Size'],
        'Store_Location_City_Type': product_data['Store_Location_City_Type'],
        'Store_Type': product_data['Store_Type']
    }

    # Convert the extracted data into a Pandas DataFrame
    input_data = pd.DataFrame([sample])

    # Make prediction (get log_price)
    predicted_sales = model.predict(input_data)[0]

    # Return the actual Predicted sales price
    return jsonify({'Predicted Sales': predicted_sales})


# Define an endpoint for batch prediction (POST request)
@product_sales_predictor_api.post('/v1/batchsales')
def predict_sales_batch():
    print(">>> Batch endpoint invoked!", flush=True)
    try:
        file = request.files.get('file')
        print(">>> File received:", file is not None, flush=True)

        #All messages used for debugging retained as it is
        input_data = pd.read_csv(file)
        print(">>> CSV loaded. Columns:", list(input_data.columns), flush=True)

        #Drop Since the below columns where not used while builing the model
        drop_cols = [
            'Product_Id',
            'Store_Id',
            'Store_Establishment_Year',
            'Product_Store_Sales_Total'
        ]
        input_data = input_data.drop(columns=[c for c in drop_cols if c in input_data.columns])
        print(">>> After column drop:", list(input_data.columns), flush=True)

        predictions = model.predict(input_data)
        predictions = [float(p) for p in predictions]

        print(">>> Predictions completed", flush=True)

        return jsonify({"predictions": predictions})

    except Exception as e:
        print(">>> ERROR:", str(e), flush=True)
        return jsonify({"error": str(e)}), 500